Modified polypropylene/ thermoplastic polyurethane blends with maleic-anhydride grafted polypropylene: blending morphology and mechanical behaviors

This study proposes using polypropylene grafted maleic anhydride (MA) to improve the interfacial compatibility between modified impact-resistant polypropylene (MPP) and thermoplastic polyurethane (TPU). The melt-compounding and injection method is used to prepare MPP/TPU/MA blends. The blending morphology, tensile behavior, flexural behavior, and impact behavior of blends are evaluated in terms of the content of TPU and MA. The SEM images show the positive influence of using MA on the compatibility between MPP and TPU, and only 1 wt% of it can efficiently decrease the difference in polarity and interfacial tension. As MA is an additional reinforcement, 100 wt% of the blends are made of MPP and TPU, indicating that more TPU means less MPP. When the blends are made of more TPU, the tensile strength of the control group (pure MPP/TPU blends) shows a decreasing trend. By contrast, MPP80/TPU20/MA3 blends have a tensile strength of 28 MPa and Young’s modulus of 927 MPa, while MPP90/TPU10/MA1 blends have the optimal flexural stress of 53.99 MPa and flexural modulus of 1493.61 MPa. Exception for MPP60/TPU40/MA1 blends, all the other experimental groups have greater impact strength as a result of using 1 wt% of MA. Specifically, MPP90/TPU10/MA1 blends have the maximum impact strength of 105.28 J/ m. The addition of MA has proven to efficiently improve the compatibility and interfacial adhesion between MPP and TPU, thereby forming an extraordinary bonding with a stabilized phase where a stress can be efficiently distributed. This study expects to design and adjust the performance of the composite blends according to the test results of SEM observation, tensile strength test, and impact strength test.